diff options
Diffstat (limited to 'drivers/iio/adc/spear_adc.c')
| -rw-r--r-- | drivers/iio/adc/spear_adc.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/drivers/iio/adc/spear_adc.c b/drivers/iio/adc/spear_adc.c index 1bc986a7009d..d93e580b3dc5 100644 --- a/drivers/iio/adc/spear_adc.c +++ b/drivers/iio/adc/spear_adc.c @@ -75,6 +75,15 @@ struct spear_adc_state { struct adc_regs_spear6xx __iomem *adc_base_spear6xx; struct clk *clk; struct completion completion; + /* + * Lock to protect the device state during a potential concurrent + * read access from userspace. Reading a raw value requires a sequence + * of register writes, then a wait for a completion callback, + * and finally a register read, during which userspace could issue + * another read request. This lock protects a read access from + * ocurring before another one has finished. + */ + struct mutex lock; u32 current_clk; u32 sampling_freq; u32 avg_samples; @@ -146,7 +155,7 @@ static int spear_adc_read_raw(struct iio_dev *indio_dev, switch (mask) { case IIO_CHAN_INFO_RAW: - mutex_lock(&indio_dev->mlock); + mutex_lock(&st->lock); status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) | SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) | @@ -159,7 +168,7 @@ static int spear_adc_read_raw(struct iio_dev *indio_dev, wait_for_completion(&st->completion); /* set by ISR */ *val = st->value; - mutex_unlock(&indio_dev->mlock); + mutex_unlock(&st->lock); return IIO_VAL_INT; @@ -187,7 +196,7 @@ static int spear_adc_write_raw(struct iio_dev *indio_dev, if (mask != IIO_CHAN_INFO_SAMP_FREQ) return -EINVAL; - mutex_lock(&indio_dev->mlock); + mutex_lock(&st->lock); if ((val < SPEAR_ADC_CLK_MIN) || (val > SPEAR_ADC_CLK_MAX) || @@ -199,7 +208,7 @@ static int spear_adc_write_raw(struct iio_dev *indio_dev, spear_adc_set_clk(st, val); out: - mutex_unlock(&indio_dev->mlock); + mutex_unlock(&st->lock); return ret; } @@ -271,6 +280,9 @@ static int spear_adc_probe(struct platform_device *pdev) } st = iio_priv(indio_dev); + + mutex_init(&st->lock); + st->np = np; /* |